The improved coupling system may, generally speaking, serve for connecting coaxial hoses respectively with a union connected in its turn with the input and output channels, and with a machine or apparatus operated by a flow of fluid under pressure between a high pressure fluid input and a low pressure fluid output.
In the U.S. Pat. No. 4,109,381 in the name of the present applicant, there are described and claimed hydraulic pruning-scissors connected with the supply of operative fluid through coaxial hoses of which the inner pipe feeds the hydraulic fluid under pressure into the pruning-scissors while the other, outer pipe returns said fluid to the supply
In such an embodiment, the rear end of the body inside which is fitted the arrangement controlling hydraulically the movable blade of the pruning scissors, is provided with a tapped recess the rear end of which is perforated axially with a bore adapted to interconnect said recess with the input of the hydraulic distributor of the pruning scissors and to house the free end of the union carried by the inner hose pipe, while the union fitted on the outer hose pipe is screwed into the tapping of said recess and bears through its free end against a rigid of disconnectable shoulder formed on the inner union which is held fast in position by the pressure exerted by the outer union screwed into the tapping.
The latter union is connected inwardly with the output of the hydraulic distributor through a passage formed in the body of the apparatus. This prior arrangement has improved substantially the execution, the handling and the operation of hydraulic pruning-scissors. However, it has been found that the rigid fitting through screwing of the ends or mouthpieces of the coaxial hose-pipes feeding and returning the fluid did not prevent the twisting of the latter during the kendling of the tool; such a twisting may jeopardize the proper flow of fluid and further damage in the hose-pipes or again cause an unscrewing of their mouth pieces.